Dyspnea/wheeze/cough/orthopnea - Dyspnea is due to pulmonary edema or pleural effusion. Cough may occur due to pulmonary edema or due to mitral valve insufficiency with left atrial enlargement and compression of the left main-stem bronchus; this latter cause may often occur in the absence of congestive heart failure. Many dogs with heart failure may not cough, whereas dyspnea, wheezes and sometimes orthopnea (difficulty breathing when lying down) are common historical findings. Some dogs will cough with relatively mild edema and others only cough with severe pulmonary edema. It appears that the speed with which the pulmonary edema develops may play a role in determining when or if cough is to develop.

Abdominal distention - due to ascites and/or

Hepatomegaly or splenomegaly.

top Clinical Evaluation of Heart Disease: The Physical Exam2 What are the physical examination findings in heart failure?

Physical examination findings may include (signs of both reduced cardiac output and elevated preload):

top Clinical Evaluation of Heart Disease: The Physical Exam3 What are pulse deficits?

Pulse deficits are present when the pulse rate is less than the heart rate. This occurs because a cardiac contraction or several contractions take place prematurely not allowing enough time for ventricular filling (preload). This results in heart beats that do not eject enough blood to generate a palpable pulse.

The presence of pulse deficits should alert the diagnostician to the occurrence of premature ectopic beats. These may be either supraventricular or ventricular in origin, only the ECG can distinguish these.

top Clinical Evaluation of Heart Disease: The Physical Exam4 What is a hepato-jugular reflux (HJR) response?

This test checks for the presence of jugular distention or jugular pulsations when pressure is placed in the region of the cranial abdomen in a ventral to dorsal direction. The animal should be standing or in sternal recumbency to perform this test.

A positive test result indicates that there is elevated pressure in the right atrium or right ventricle. If one were to classify an elevated pressure in the right heart as mild, moderate or severe, venous distention at rest indicates a severe elevation in pressure, whereas a positive HJR indicates a moderate elevation in pressure. Patients with a mild elevation in pressure to the right heart cannot be identified on physical examination.

top Clinical Evaluation of Heart Disease: The Physical Exam5 How do I interpret the arterial pulse?

top Clinical Evaluation of Heart Disease: The Physical Exam7 What abnormalities can be detected by cardiac palpation?

Precordial palpation is useful to:

detect a thrill - a thrill refers to a vibration on the chest wall due to fluid turbulence within the heart that also causes a heart murmur on auscultation. Only the very loudest heart murmurs will be accompanied by a thrill

detect dysrhythmias

suspicion of cardiomegaly

location of apex beat - usually on left - some disorders will cause the apex beat to shift to the right chest wall

top Clinical Evaluation of Heart Disease: The Physical Exam8 What can be learned from auscultation?

Auscultation remains the most useful and expedient assessment of the cardiac patient. It can frequently result in a definitive diagnosis or when combined with the signalment and history can often provide a strong differential diagnosis.

Other than for detecting asystole, auscultation cannot provide definitive evidence of heart failure. Rarely, individuals may have heart failure in the face of normal heart sounds and cardiac rhythm. The finding of gallop sounds is often very strong evidence of severe myocardial dysfunction. The presence of a murmur does not equate with heart failure. In fact, most patients with a heart murmur do not have heart failure.

top Clinical Evaluation of Heart Disease: The Physical Exam9 What are some important technical aspects about stethoscopes and auscultation?

1. Most of the disorders that promote abnormal heart sounds produce sounds that do not fall into the audible range. Thus, to detect those few that do fall into the audible range, careful auscultation is necessary to locate these sounds.

2. For the best sound reproduction, consider the following:

A double lumen scope is better than a single lumen

Shorter tubing is better than longer tubing

The best results occur if the room is quiet and one person is dedicated to controlling the head of the patient including closing the mouth to reduce panting. An attempt should be made to promote ease of breathing and reduce anxiety on the part of the patient.

The diaphragm is better for high frequency sounds such as most systolic murmurs, clicks, and breath sounds

The bell is better for low frequency sounds such as diastolic murmurs, and gallop sounds. If the bell is pressed tightly to the skin, the skin will function like a diaphragm and so the utility of using a bell will be lost.

3. Only auscult a patient when in the standing or sitting position. Auscultation of the patient in lateral or dorsal recumbency can result in creating false murmur like sounds (perhaps rubbing sounds) and/or impairs our ability to localize the PMI for a "real" murmur.

top Clinical Evaluation of Heart Disease: The Physical Exam10 What is the origin of the normal heart sounds, S1 and S2?

S1

High frequency sound

Heard best over the left apex

With respect to timing: is associated with closure of the AV valves

It signals the onset of systole and correlates in timing with the QRS of the accompanying ECG.

Origin is controversial. Probably due to the rapid deceleration of the column of blood into the ventricle at the end of filling which sets the heart into vibration.

The intensity of S1 is probably mainly related to the velocity of closure of the AV valves.

S2

High frequency sound

Heard best over the left base

With respect to timing: is associated with closure of the semilunar valves

It signals the end of ventricular ejection and occurs corresponding to after the end of the T wave on an accompanying ECG.

Origin is controversial.

The intensity of S2 probably increases as the velocity of semilunar valve closure increases.

top Clinical Evaluation of Heart Disease: The Physical Exam11 What are heart murmurs?

Heart murmurs are abnormal, extra sounds that are of a relatively long duration.

Heart murmurs occur as a result of turbulence within the heart created by disturbed blood flow.

Reynolds number defines the variables that promote disturbed (non laminar) flow in a vessel or chamber. When Reynolds Number exceeds a critical value flow becomes turbulent.

Reynolds No = (Area)(Velocity)(Density) / Viscosity

Area = cross-sectional area of the chamber, orifice, or vessel; Velocity = velocity of blood flow (note that this is related to the area); Density = density of blood; Viscosity = viscosity of blood (affected mainly by the red blood cell count and protein count)

Blood flow turbulence can be created by high-velocity flow, flow from a narrow region into a larger area, or low blood viscosity.

top Clinical Evaluation of Heart Disease: The Physical Exam12 What causes heart murmurs?

May be observed in young adults likely associated with ejection of blood into the great vessels

< grade 3

occur in early to mid systole

Associated with increase in blood flow across a normal valvular orifice as with flow across the pulmonic valve in a VSD and ASD or across the aortic valve in bradycardia such as 3rd degree AV block

Anything that muffles the heart sounds can obscure a murmur such as obesity, thoracic effusions, or loud respiratory sounds.

top Clinical Evaluation of Heart Disease: The Physical Exam13 Can heart murmurs occur in the absence of anatomic or physiologic changes to the heart?

Functional (physiologic) heart murmurs occur in the absence of cardiac disease in a variety of situations. These murmurs are most commonly identified in the growing young dog, where they are referred to as innocent murmurs. These murmurs should resolve by 6 months of age, and tend to have the following characteristics:

soft, low intensity sounds (grade 1/6 to 2/6)

occur early in systole

PMI over the left base

may vary in intensity with a change in HR or body position

It is my belief that similar innocent heart murmurs may also occur in the adult, particularly of large and giant breed dogs.

Functional (physiologic) murmurs may also occur:

in athletes

in pathologic states such as fever, anemia, or hypoproteinemia

These are important features to distinguish innocent murmurs from congenital heart murmurs.

top Clinical Evaluation of Heart Disease: The Physical Exam14 How does the detection of a heart murmur help us determine the type of heart disease?

A presumptive diagnosis is usually possible based primarily on the timing of the heart murmur, and the point of maximal intensity (PMI) of the murmur.

Note that other features of the murmur also aid in identifying the etiology and they include:

The intensity (loudness)

The frequency (pitch)

The configuration (shape)

The quality

The duration

The direction of radiation

These "other features" are clearly of secondary use and less sensitive than the primary features of timing and PMI.

Point of Maximal Intensity (PMI):

The PMI refers to the location where the murmur is loudest.

The left chest wall is typically divided with respect to PMI into two positions.

left heart base (includes both the pulmonic valve and aortic valve areas, and discriminating between these two is often problematic)

left heart apex (mitral valve area)

The right chest wall is typically divided with respect to PMI into two positions.

mid heart (tricuspid valve area)

sternal border (typical of a VSD)

Timing:

Timing of murmurs, at the PMI, is generally divided into one of three classes:

systolic (occurring during systole)

diastolic (occurring during diastole)

continuous (present at all times)

Systolic murmurs:

The very vast majority of murmurs are systolic

When soft they are usually early in systole and disturb the end of S1. S1 often appears slurred in these cases as opposed to ending abruptly as is normally the case.

The careful clinician focuses on the end of S1 for soft systolic murmurs.

Holosystolic murmur: refers to a systolic murmur that begins during or immediately after S1 and ends with the onset of S2

Pansystolic murmur: refers to a systolic murmur that begins during or immediately after S1 and continues into and obscures S2 (note that left ventricular pressure continues to be greater than left atrial pressure after aortic valve closure - during isovolumetric relaxation).

Using the timing and PMI of a murmur, the following algorithm may be used to arrive at a presumptive diagnosis:

Recall causes for a continuous murmur: PDA or Arteriovenous Fistula

Intensity:

The intensity of the murmur at its origin is related to (Blood flow velocity) x (Rate of flow). Overall, the intensity of a heart murmur is not related to the severity of the lesion; however for some diseases there is a rough correlation between the intensity of the murmur and the severity of the lesion such as:

Mitral valve insufficiency

Aortic / subaortic valve stenosis

Pulmonic valve stenosis

The intensity of a murmur is graded on a scale of 1 to 6:

Grade 1 = a very soft, localized murmur detected only after several minutes of listening.

Grade 2 = a soft murmur, heard immediately but localized to a small area.

Grade 3 = a moderately intense murmur that is readily detected and detected over more than one location.

Grade 4 = a moderately intense or loud murmur, detected over several areas, usually both sides of the chest, however a precordial thrill is not detected in this case.

Grade 5 = a loud murmur accompanied by a precordial thrill over the point of maximal intensity.

Grade 6 = a very loud murmur accompanied by a precordial thrill and the murmur is detected when the stethoscope is pulled slightly off the chest wall.

top Clinical Evaluation of Heart Disease: The Physical Exam15 What are some special considerations for heart murmurs in cats?

In the cat, the areas of typical location for murmurs in dogs are not useful. Murmurs are typically loudest located along the sternum or just off the right or left side of the sternum. Murmurs can be located in the caudal part of the thorax or cranial part of the thorax in the cat.

Cranial sternal murmurs in cats are common, usually functional, and probably due to ejection of blood into a dilated aorta or dynamic right ventricular outflow tract obstruction.

VSD is probably the most common congenital cause for a murmur.

MR is probably the most common acquired cause for a murmur.

About 20-25% of murmurs in cats are not associated with any substantial pathology.

S3 and S4 sounds are louder than in dogs, greater intensity and higher frequency.

S4 gallops may be normal in older stressed cats. Since their heart rates are usually high it can be difficult to discriminate between an S3 and an S4 in the cat.

top Clinical Evaluation of Heart Disease: The Physical Exam16 What other abnormalities may be detected by cardiac auscultation and what is their significance?

GALLOPS:

result in a tripling or quadrupling of the heart sounds, resembling the canter of a horse

best heard with the bell of the stethoscope

S3 gallop (ventricular gallop)

Low frequency sound

Occurs shortly after the S2 sound, at the beginning of diastole, during the rapid filling phase.

Called a ventricular gallop

Not normal in dogs and cats. Indicates ventricular failure. May be an early finding and the only auscultatory evidence of heart failure.

Indicates diastolic dysfunction

Associated with reduced compliance of the ventricle while filling under conditions of high filling pressures (stiffer ventricle).

Caused by the sudden termination of longitudinal expansion of the ventricular wall during brisk early diastolic filling during the period of rapid ventricular filling.

Indicates severe myocardial disease

S4 gallop (atrial gallop)

Low frequency sound

Occurs shortly before the S1 sound, at the end of diastole, during atrial contraction.

Called an atrial gallop

Not normal in dogs and cats. Usually indicates ventricular failure. May be the only auscultatory evidence of heart failure.

Indicates diastolic dysfunction

Associated with the atria trying to force blood into an already over-distended ventricle or because the atria are forcing blood into a stiff ventricle. Atrial contraction is required for an audible S4 sound. Thus it does not occur in atrial fibrillation.

Occurs in disorders with impaired relaxation of the ventricle typical of disorders of concentric hypertrophy

May be a normal finding in older stressed cats

Summation gallop

At fast heart rates an S3 and S4 gallop will superimpose to cause one sound called a summation gallop.

A split S1 is due to asynchronous closure of the AV valves, which may occur with conduction disturbances such as bundle branch block or ectopic ventricular beats or with mechanical disturbances in valve closure such as mitral or tricuspid stenosis.

A split S2 is due to asynchronous closure of the semilunar valves. This may be heard in normal large breed dogs during inspiration as there is more right ventricular filling and longer right ventricular ejection time during inspiration. Abnormal causes of split S2 include 1) conduction disturbances such as bundle branch block and ectopic ventricular beats, 2) delayed closure of the pulmonic valve such as with pulmonary hypertension, pulmonic stenosis, or an atrial septal defect, or 3) delayed closure of the aortic valve such as with systemic hypertension or aortic stenosis.

periodicity with the heart rhythm (then it is difficult to distinguish from a continuous murmur)

periodicity with respiration

caused by fibrin present on the pleural surfaces of chest wall, lungs, or pericardium

ARRYTHMIAS:

Isolated premature beats or pairs or short bursts of premature beats result in disturbances to the cadence of the heart rhythm.

Premature beats may result in only the presence of abnormally long pauses between beats. If the premature beat is extremely early (premature) no additional heart sounds will be detected, only the presence of the abnormal pause that follows. One might suspect that so-called "dropped beats" are occurring. PVCs tend to cause longer pauses than SVPCs.

If the premature beat is slightly less premature only an S2 will be detected, so that the rhythm will sound like S1 then S2 and another S2 in rapid succession. This could be misinterpreted as a gallop. Gallops should not be intermittent like premature beats and they are not followed by an abnormal pause.

Even less premature beats may be associated with both an early S1 and S2.

A regular rhythm does not mean the rhythm is necessarily normal/sinus. Sustained ventricular or supraventricular tachycardia can be associated with a regular rhythm.

Radiography cannot detect a reduction in cardiac output for the needs of the tissue (heart failure) but can provide evidence of pulmonary congestion to suggest congestive heart failure (pulmonary venous engorgement, pulmonary interstitial edema, and obscuring and enlargement of the cardiac silhouette).

Radiography provides the most readily available means to identify pulmonary edema and pulmonary venous congestion. Because the vast majority of cases of pulmonary edema are due to congestive heart failure - then the finding of pulmonary edema is strong evidence of congestive heart failure.

Since pulmonary venous congestion (distention) will/must occur prior to the development of cardiogenic pulmonary edema, to identify the presence of pulmonary venous congestion is also strong evidence of congestive heart failure.

top Clinical Evaluation of Heart Disease: Radiographic Evaluation18 What are the radiographic features of pulmonary venous distention and pulmonary edema?

On the lateral view the pulmonary veins to the cranial lung lobes are greater than 75% the width of the proximal 1/3 of the fourth rib

The pulmonary vein to the cranial lung lobe is obviously larger than its accompanying pulmonary artery (normally they are of equal width)

Pulmonary edema refers to an abnormal accumulation of fluid in the interstitium and/or the alveoli of the lungs. As fluid weeps out of the capillaries, at first it accumulates in the perivascular and peribronchial interstitial spaces (producing silhouetting of the vessels, and/or peribronchial pattern on radiographs). Continued fluid accumulation results in edema of alveolar walls and ultimately, alveolar edema (producing air-bronchograms or coalescent [so called cotton-like] pulmonary densities).

Although alveolar edema is usually preceded by interstitial edema, many clinical cases represent a mixture of interstitial and alveolar edema.

Radiographic Appearance:

Venous engorgement - distention of the veins.

Interstitial edema - shows a clouding (or silhouetting) of the pulmonary vasculature (perivascular pattern). The walls of the pulmonary vessels are obscured by edema fluid. A peribronchial pulmonary pattern (the most common sign of interstitial edema noted in the dog) also may occur as noted. This pattern is characterized by thickened airway walls. Normally the airway walls are not discernible radiographically after the third generation bronchi due to the lack of cartilaginous support. We typically infer the presence of a bronchus due its position between the artery and vein that lie on each side. The prominent appearance of airway walls throughout the lungs indicates a peribronchial lung pattern, which implies a cellular and/or fluid accumulation in the walls rendering them visible. On cross-section the airway walls are "donut-like", on long axis view they are "railway tracks-like."

Single chamber enlargement is unusual and therefore enlargement in one chamber tends to cause enlargement in other areas of the heart.

Some general guidelines on cardiac size in the cat:

The heart is more elongated and elliptical in shape than in the dog on the lateral view.

The ventricular area occupies about 2 to 2 1/2 intercostal spaces in the lateral view.

In the lateral view the cat heart tends to be more horizontal; as cats age, the heart tends to horizontalize even more (called a "lazy" heart).

In the D/V or V/D projection, the cat heart is more oval and thinner than the dog. The cardiac apex usually lies on the midline.

top Clinical Evaluation of Heart Disease: Radiographic Evaluation21 How can vertebral heart size (VHS) be used to evaluate heart size?

Vertebral Heart Size (VHS) is a technique that measures the width and breadth of the heart and compares it to the length of the vertebral bodies. It can be useful because the measurements are independent of respiration and the position of the heart within the chest. However, because of the test's low sensitivity, a normal VHS does not rule out an enlarged heart. It also does not rule out the possibility of cardiac disease that does not have an effect on heart size.

To calculate VHS, use a lateral view that clearly shows the T4-T13 vertebrae, with minimal rotation of the thorax (rib arches and costochondral junctions should be aligned).
Long axis: Measure the distance (using a ruler or piece of paper) from the carina to the apex of the heart.
Short axis: Measure the widest part of the heart on an axis perpendicular to the long axis.
Compare to vertebrae: Starting from the cranial edge of the T4 vertebral body, measure the length of the axes by the number of vertebrae. Measure to 0.1 of a vertebral body. The vertebral heart size is the sum of the length of the short and the long axes in vertebrae (VHS = long + short).

Reference intervals for VHS:

Normal dogs: 8.5-10.7

Boxers: 10.3-12.6

Labrador Retrievers: 9.7-11.7

Cavalier King Charles Spaniels: 9.9-11.7

Cats: 6.7-8.1

top Clinical Evaluation of Heart Disease: Radiographic Evaluation22 What abnormalities of the great vessels might be identified by routine radiography?

Radiography is a simple means to determine changes in the great vessels.

Distention of the aorta in the region of the aortic arch with aortic stenosis:

may not be apparent unless aortic stenosis (or subaortic) is severe

Dilation of the main pulmonary artery (MPA):

due to pulmonic stenosis, heartworm disease, or pulmonary artery hypertension

Pulmonary over-circulation:

left to right shunt

Pulmonary under-circulation:

right to left shunt

under-perfusion/hypovolemia/dehydration

Caudal vena caval enlargement:

Caudal vena cava Present if the caudal vena cava is persistently of greater diameter than the descending thoracic aorta on the lateral view (normally they are roughly equal).

Suggests right heart failure with elevated volumes in the caudal vena cava.

top Clinical Evaluation of Heart Disease: Radiographic Evaluation23 What radiographic features might suggest the presence of heartworm disease?

There is no blood test that can definitively determine the existence of heart failure. However, the detection of certain circulating hormones or enzymes, so-called biomarkers, may provide strong evidence in support of heart failure or even heart disease. See below.

top Clinical Evaluation of Heart Disease: Hematologic Evaluation28 What cardiac abnormalities can be diagnosed by blood work?

A number of findings can support a reduced cardiac output:

evidence of reduced renal perfusion (reduced GFR)

increase BUN/creatinine or reduced urinary output

depressed venous oxygen tension (venous pO2) levels

elevated lactate levels

reduced serum sodium

Muscle enzyme elevations (CPK, SGOT, LDH) are almost uniformly of no value in detecting heart disease of domestic animals; isoenzymes may be of more value to detect myocardial necrosis.

Circulating cardiac troponin I (cTnI) is a general marker of cardiac myocyte injury. It is elevated in a number of canine and feline cardiac diseases, including dilated and hypertrophic cardiomyopathies, subaortic stenosis, and chronic mitral valve disease, but also in other diseases that may secondarily cause myocardial injury. In dilated cardiomyopathy, cTnI levels may relate to prognosis. Several human cTnI assays have been validated in dogs and cats.

Plasma norepinephrine is elevated in all causes of heart failure and the level relates to prognosis.

Plasma aldosterone and angiotensin II are elevated in heart failure.

Atrial Natriuretic Peptide (ANP) and Brain Natriuretic Peptide (BNP) are elevated in humans, cats, and dogs with heart failure of various causes. For more information on BNP see the next question.

Sensitivity and specificity are reported to be 90% and 85% respectively, however this may apply mostly to the detection of severe disease. Therefore recognize that there is the potential for false negatives, particularly in the case of mild to moderate disease. False positives are also possible.

For cases that are too fragile for diagnostics or that can't afford echocardiography.

Radiographs are always indicated in the presence of respiratory signs, however findings can sometimes be inconclusive.

Recommendations:

NT-proBNP > 270 pmol/l is highly likely to indicate the presence of CHF

Cats with NT-proBNP between 50-270 pmol/l likely have heart disease but may or may not have CHF.

Use of the NT-proBNP test in Dogs:

Where might there be a place for this test in dogs?

To identify dogs with asymptomatic (occult) DCM

To differentiate between primary respiratory disease and CHF as the cause for respiratory clinical signs

To assess prognosis and guide therapy

To identify dogs with asymptomatic heart disease:

Recommendations:

NT-proBNP > 900 pmol/l is likely to indicate the presence of heart disease

Recognize again that both false positives and false negatives will occur.

Dogs with DCM tend to have higher values than dogs with CMVI

The more advanced the heart disease the higher the levels of NT-proBNP

Echocardiography (ultrasound of the heart) is the most expedient means of detecting and quantifying a weakened heart muscle (systolic dysfunction) or abnormal filling (diastolic dysfunction). It is also ideal to detect a great number of other disorders that contribute to heart disease and heart failure.

Although echocardiography cannot definitively determine if heart failure is present (that is, the adequacy of cardiac performance), it can potentially provide strong evidence to support or refute the presence of heart failure.

top Clinical Evaluation of Heart Disease: Echocardiographic Evaluation31 What other abnormalities can be diagnosed by echocardiography?

Echocardiography can detect:

Changes in chamber dimensions and wall thicknesses which can suggest the etiology of congenital or acquired heart disorders

Chronic valvular disease

Dilated cardiomyopathy

Hypertrophic cardiomyopathy

Pericardial disease

Bacterial endocarditis

Cardiac tumours

Doppler echocardiography can be used to detect and quantify stenotic and insufficient valvular heart disease and pulmonary artery hypertension

Diastolic disorders of myocardial function

top Clinical Evaluation of Heart Disease: Echocardiographic Evaluation32 What is Doppler echocardiography? How is it useful?

Doppler echocardiography allows for the detection of abnormal blood flow patterns as well as the velocity of blood cells as they move throughout the heart.

Doppler echocardiography allows for the diagnosis and quantification of the severity of: